The present invention relates to portable coolers for foodstuffs, beverages and other articles such as biological tissue specimens and temperature sensitive chemicals and pharmaceuticals. More specifically the present invention relates to portable coolers that provide refrigerant as a built-in part of the cooler itself and to wall constructions for coolers that allow sheets of refrigerant cubes to be incorporated into the structure of the cooler itself.
Many types of portable coolers and ice chests exist that are designed for allowing food and beverages to be kept chilled for limited periods. Some coolers have a hard shell of molded plastic that gives them a rigid construction. Other types of coolers feature exterior layers of tough but pliable fabric that are sewn together to form a more flexible containment structure. Many portable coolers are used simply to provide thermal insulation and keep their contents cool by protecting against rapid heating. Unfortunately, under warm conditions these types of coolers can at most keep their contents cool for short periods of time on the order of two or three hours. Most coolers are used with blocks or cubes of ice or frozen gel solution that are usually encapsulated in plastic containers or in small polyvinyl packets. These containers or packets of freezable material are separate and removable from the coolers and are usually purchased as separate products. Prior to use the containers or packets are placed in a freezer until they become frozen solid. When placed in a cooler these frozen materials actively cool and chill the contents of the cooler as they absorb heat energy corresponding to their heat of fusion and low starting temperature. This approach can provide more long lasting effects and can even cool down beverages and food which start at room temperature. However, the containers and packets of freezable material can be inconvenient and awkward to handle and position within the cooler and can take up a lot of otherwise usable space within the interior of the cooler if they are not designed to compactly fit within the cooler.
Portable coolers are designed to be simply and easily manufactured while providing the greatest amount of cooling possible and at the same time to be as convenient to use and as visually appealing to the consumer as possible. Some existing patents exemplify current designs and illustrate the prior art pertinent to the present invention.
U.S. Pat. No. 4,324,111 to Edwards entitled Freezing Gel Containment Structure and Method provides an active cooling structure composed of adjacent plastic tubes of encapsulated freezing gel that form rigid panels for surrounding a bottle or the like. The tubes may be encased in decorative covers but the tubes and covers are not formed into closed containment structures.
U.S. Pat. No. 4,183,226 to Moore entitled Refrigerated Beverage Holder similarly describes a cylindrical sleeve of reusable refrigerant in the form of ice packs shown as elongated sealed sections of plastic. The sealed sections or bars of encapsulated refrigerant are disposed within the beverage can holder along the interior of its outer insulated wall in the space between the beverage can and the holder. The beverage can holder may include inner walls defining an annular section for containing the refrigerant.
U.S. Pat. No. 5,570,588 to Lowe entitled Freezable Insert Cooler provides a rigid molded plastic cooler body having a rectangular shape and including hollow perimeter sidewalls. A freezable gel pack insert is positioned within one or more of the hollow perimeter sidewalls and is removable so that it can be conveniently frozen apart from the cooler. The gel pack is described as being constructed of heat sealed webs that may include integral hinges.
U.S. Pat. No. 4,311,022 to Hall entitled Foldable Ice Pack provides a ice pack having a large number of separate refrigerant containing compartments within a multiple layered wall assembly of foldable plastic sheet material. The outer walls of the assembly are intended to help control the accumulation of condensation. The inner walls are heat sealed between adjacent compartments to define the compartments and form webbing strips between them. Among other things, the ice pack is described as being used with ice chests and lunch boxes.
U.S. Pat. No. 4,700,706 to Munch entitled Cold and Warm Pack For Physiotherapy And The Like describes a sleeve composed of two layers of flexible foil that are bonded together. One layer of foil is planar while the other defines cups and flanged edges. The cups are filled with special temperature storage filling material so as to function as cold or warm packs for medical use.
U.S. Pat. No. 2,602,302 to Poux entitled combination Ice and Hot Pack provides an elongated rectangular body having a series of sealed spaced-apart compartments containing water or some other refrigerant fluid. The body member is described as being composed of thin rubber or plastic sheeting which allows the member to be readily flexed. The article may be prepared for use by being placed in a freezer and may be employed for therapeutic or for the heating and cooling of other articles such as foods.
U.S. Pat. No. 4,931,333 to Henry entitled Thermal Packaging Assembly describes the use of capsules having a flexible outer skin and containing a thermal controlling agent such as a refrigerant. The capsules have sloping, rounded outer surfaces and may be efficiently packed in large numbers around items to be maintained at a controlled temperature. The capsules may also be provided in a continuous sheet in bubble pack form for being wrapped around items as packing.